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From: Jakub Jelinek <jakub@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r14-8423] convert: Fix test for out of bounds shift count [PR113574] Date: Thu, 25 Jan 2024 12:16:03 +0000 (GMT) [thread overview] Message-ID: <20240125121603.7D2A23858C53@sourceware.org> (raw) https://gcc.gnu.org/g:fb1b7e2fec951ba0bf4f68fac6a16929f4f63910 commit r14-8423-gfb1b7e2fec951ba0bf4f68fac6a16929f4f63910 Author: Jakub Jelinek <jakub@redhat.com> Date: Thu Jan 25 13:15:23 2024 +0100 convert: Fix test for out of bounds shift count [PR113574] The following patch is miscompiled, because convert_to_integer_1 for LSHIFT_EXPR tests if the INTEGER_CST shift count is too high, but incorrectly compares it against TYPE_SIZE rather than TYPE_PRECISION. The type in question is unsigned _BitInt(1), which has TYPE_PRECISION 1, TYPE_SIZE 8, and the shift count is 2 in that case. 2024-01-25 Jakub Jelinek <jakub@redhat.com> PR middle-end/113574 * convert.cc (convert_to_integer_1) <case LSHIFT_EXPR>: Compare shift count against TYPE_PRECISION rather than TYPE_SIZE. * gcc.dg/torture/bitint-52.c: New test. Diff: --- gcc/convert.cc | 3 ++- gcc/testsuite/gcc.dg/torture/bitint-52.c | 23 +++++++++++++++++++++++ 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/gcc/convert.cc b/gcc/convert.cc index 179f5e69008..5ad24ad2c08 100644 --- a/gcc/convert.cc +++ b/gcc/convert.cc @@ -762,7 +762,8 @@ convert_to_integer_1 (tree type, tree expr, bool dofold) { /* If shift count is less than the width of the truncated type, really shift. */ - if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type))) + if (wi::to_widest (TREE_OPERAND (expr, 1)) + < TYPE_PRECISION (type)) /* In this case, shifting is like multiplication. */ goto trunc1; else diff --git a/gcc/testsuite/gcc.dg/torture/bitint-52.c b/gcc/testsuite/gcc.dg/torture/bitint-52.c new file mode 100644 index 00000000000..d2896da2f9a --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/bitint-52.c @@ -0,0 +1,23 @@ +/* PR middle-end/113574 */ +/* { dg-do run { target bitint } } */ +/* { dg-options "-std=c23 -pedantic-errors" } */ +/* { dg-skip-if "" { ! run_expensive_tests } { "*" } { "-O0" "-O2" } } */ +/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */ + +unsigned _BitInt(1) a; +unsigned _BitInt(8) b; + +void +foo (unsigned _BitInt(16) x) +{ + a += (x << 2) | b; +} + +int +main () +{ + foo (0xfef1uwb); + if (a) + __builtin_abort (); + return 0; +}
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